The HP logo is displayed on the entrance to the Hewlett-Packard headquarters in Palo Alto, Calif. / Justin Sullivan Getty Images

by Scott Martin, USA TODAY

by Scott Martin, USA TODAY

SAN FRANCISCO - The war of words escalated today between Hewlett-Packard and former Autonomy CEO Mike Lynch in the wake of the computing giant's gargantuan $8.8 billion writedown stemming from allegations of accounting improprieties at the software company it acquired last year.

Lynch on Tuesday sent an open letter to HP's board of directors, saying it was "shocking" that the company made the allegations public without first contacting him. "I utterly reject all allegation of impropriety," he wrote. He went on in the letter to defend the accounting done at Autonomy, which was handled by Deloitte.

Last week, Hewlett-Packard dropped the bombshell that it was taking the massive writedown against Autonomy. The troubled computing behemoth alleged that Autonomy's management used faulty accounting, misrepresentations and disclosure failures to inflate the company's financial metrics prior to HP's acquisition of the company.

Following the writedown at HP and accusations against Autonomy's management, Lynch appeared on TV that very day to argue the charges.

Hewlett-Packard agreed to acquire the British software company for more than $11 billion in October of last year. The deal was widely viewed as overpriced at the time.

HP on Tuesday quickly shot back in response to Lynch's letter to the board. The company said it believes it has uncovered extensive evidence of a willful effort on the behalf of some of Autonomy's employees to inflate its underlying financial metrics. It said it was an effort to mislead investors and potential buyers.

HP said the matter is being looked at by the UK Serious Fraud Office, the U.S. Securities and Exchange Commission's Enforcement Division and the U.S. Department of Justice.

"While Dr. Lynch is eager for a debate, we believe the legal process is the correct method in which to bring out the facts and take action on behalf of our shareholders. In that setting, we look forward to hearing Dr. Lynch and other former Autonomy employees answer questions under penalty of perjury," the company said in a statement.